﻿using System;

namespace WileRangeSum
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("a = ");
            int a = int.Parse(Console.ReadLine());

            Console.Write("b = ");
            int b = int.Parse(Console.ReadLine());

            if (a < b)
            {
                int i = a;
                int s = 0;

                while (i <= b)
                {
                    s = s + i;
                    i = i + 1;
                }

                Console.WriteLine("s = " + s);
            }
            else
            {
                Console.WriteLine("a should be less than b");
            }
        }
    }
}
